This invention relates to vehicular snow skis and, in particular, to a steering keel bar that can be secured to the undersurface of a vehicular snow ski.
Skis have been available for centuries for use on humans, sleighs, and various other snow vehicles including snowmobiles. Only until the last 50 years or so have these skis incorporated or included what have been referred to as wear or steering keel bars, runners, skags, and the like as depicted, for example, in U.S. Pat. No. 3,732,939 of Samson. The Samson runner blade is affixed to the bottom surface of a ski by three threaded studs with the front and rear ends of the bar bent so as to tuck into the bottom of the ski. This method of attachment is even popular today.
A wear, steering keel, or runner bar can perform several functions. As one name implies, a wear bar is used to lengthen the life of the under or bottom surface of the ski by focusing the contact or wear on the bar when in contact with the ground or hard surfaces. As a steering keel bar, the bar extends downwards, as in a watercraft, to stabilize and improve the steering responsiveness and capability of the ski.
The Samson patent also discloses the use of carbide chips or inserts that are affixed to the bottom of the bar to improve cornering or turning on ice or compacted snow. This is similar to ice skates having a cutting edge blade. In addition, the chips or inserts improve the wear characteristics of the bar as well as the ski.
The wear bar disclosed in the Samson patent, as well as many produced by manufacturers today, exhibits a circular cross-sectional shape with a notched longitudinal recess for affixing a chip or insert therein. The insert can be square or triangular bar stock for positioning in the wear bar recess. Wear bars also utilize inserts that have triangular or wedge-shaped configurations to further accentuate the pointed bottom edge of the bar presented to the ground, ice, or snow surface.
The problem with these round or wedge shaped wear bars is that the side of the bar directs snow or other material around or, more particularly, in a downward direction to escape causing the steering keel bar and ski to lose adhesion in a hard cornering situation. In extreme cases, dangerous loss of control can occur as the snow or other material causes the bar and ski to actually lift.
The foregoing problems and disadvantages are solved and a technical advantage is achieved in a preferred embodiment of an illustrative vehicular snow ski steering keel bar in which the side surface is shaped to catch, collect, and/or compact snow and/or other material coming in proximity or contact therewith to significantly improve steering control of the bar during turning and/or cornering. By collecting and/or compacting the snow and/or other material, greater adhesion is achieved by the bar causing cornering control to improve dramatically. In an illustrative embodiment, the side surface of the bar includes first and second side surface portions that extend or project out to first and second lateral extensions of the bar, respectively. The side surface also advantageously includes a recessed surface portion that is disposed between and recessed in from each of the first and second lateral extensions to collect and/or compact snow therein. This compacted snow advantageously provides additional lateral support to the steering keel bar during cornering to maintain stability and control of the bar.
Unlike prior art bars, the steering keel bar of the present invention includes a side surface portion that extends laterally outward to a lateral extension that is below the recessed surface portion of the bar. This lateral extension of the bar further advantageously facilitates compacting of snow and/or other material in the recessed side portion and allows the compacted snow to exert a downward force on the steering keel bar, thus providing additional stability and control during turning and cornering. This is in direct contrast to prior art steering keel bars where the snow is simply directed downward and under the bar that results in the bar being pushed upwards to lessen and even lose control during hard turning and cornering.
The first and second side surface portions of the steering keel bar extend not only outward to lateral extensions, but also extend longitudinally at least partially along the bar. The recessed surface portion also extends longitudinally along the bar between and recessed in from the lateral extensions. The first and second side portions combine to form any one or a plurality of cross-sectional shapes for the steering keel bar. In one embodiment, the side surface portions are convex surface portions. The recessed surface portion includes a concave surface portion, and cooperates with the side surface portions to form an hourglass shape for the transverse, cross-sectional shape of the bar. In the preferred embodiment, the side or lateral surfaces of the bar are mirror images of each other, thus forming the cross-sectional hourglass shape. The width between the lateral extensions of the upper and lower side surface portions of the lateral side surfaces can be the same or different widths to accommodate different control features for the bar. More aggressive steering control can be advantageously achieved as the width of the lower side surface portion extensions are increased with respect to the waist section of the hourglass shape and/or the width of the upper side surface portion extensions.
The cross-sectional shape of the steering keel bar can also advantageously vary longitudinally along the bar. The width or extent of the extensions can vary to provide more or less aggressive steering control to the front end portion of the bar relative to the intermediate and rear end portions of the bar. The variance in the cross-sectional shape of the bar can be advantageously used to correct or fine tune the under steer and/or over steer properties of the bar, as well as the ski and vehicle to which it is normally attached. The side surface portions of the first and second sides are commonly mirror images, but can be also of different configurations or vertically offset from one another.
In another preferred embodiment, the recessed surface portion of a side surface can be flat adjacent surfaces with a predetermined angle therebetween. The angle can advantageously be altered to alter the flow of material in the recessed surface portion from a laminar to a turbulent flow, thus also affecting the compacting of the snow. Sharper angles create greater turbulent flow, whereas the smooth or rounded side surface portions provide cleaner or laminar flow, thus providing greater snow compaction. These flat surfaces can be utilized to form a saw-tooth or zigzag, cross-sectional shape for the bar.
To improve the wear and/or steering control properties of the steering keel bar, inserts of usually a harder material than that of the bar are affixed to the bottom surface of the steering keel bar. Any of the cross-sectional shapes of the bar can be configured with or without the inserts. Advantageously, the inserts can be disposed along the length of the bar and in combination with various cross-sectional shapes to alter or fine tune the overall steering control of the bar. The first and second sides can also have different side surface portion shapes, but are commonly mirror images of each other.
Threaded studs are advantageously affixed to the top surface of the steering keel bar to attach the bar to the keel or undersurface of a vehicle ski such as, for example, a snowmobile ski.